The present invention relates, generally, to a method for sending text messages in a telecommunication network and, in particular, to an intelligent network and a system for implementing the method.
Mobile telecommunication terminals (mobile phones) are widely used both in the business and the private sectors due to the significant advantages they have compared with fixed network terminals. The possibility of practically unlimited accessibility even for subscribers with a high level of personal mobility has been one the main reasons for this, with the full coverage of the GSM network allowing international use too. The operators of terrestrial cellular networks, such as the GSM network, also offer subscribers services not offered by the fixed network. An example of such a service is the receiving and sending of short text messages, generally known as SMS (Short Message Service) messages.
SMS is a GSM network service for sending short text messages of up to 160 characters. The data for the SMS is transferred in the signaling channel and not a useful channel, so SMS data can be transferred to one of the relevant network operator's switching points, even during a call. If the relevant recipient terminal of the short message is not accessible at the time, the message is buffered in the switching center for a specific period (usually between 48 hours and 2 weeks) and forwarded at a later time, when the recipient terminal is once again accessible.
The SMS service therefore offers an uncomplicated and fast option for sending texts with a typically maximum length of 160 characters via cellular networks. Ongoing and foreseeable developments in this area will make greater use of further applications such as reservation confirmations, advertising or bank transactions. Marketing specialists for the international mobile telephone suppliers have recognized the significance of these and will disseminate these new applications beyond the current target groups (who just use text messages for correspondence). An example of this might be the further developments of the original SMS service, known as EMS (Enhanced Messaging Service) or MMS (Multimedia Messaging Service).
The increasing dissemination of mobile telecommunication terminals means that what is known as the prepaid method is also a significant component of the payment system. This method of payment, also sometimes referred to as the “credit method” is the original name for the option of purchasing an SIM card with an associated maximum total charge as credit against prepayment. Calls can then be made with this card for as long as the remaining credit allows. Once the credit has been used up, a new card must be purchased and inserted in the device or the card must be topped up.
The prepaid method is now used increasingly for mobile telecommunication because of its significant advantages from the users' and operators' points of view. Users, for example, are not subject to a fixed monthly basic fee and long-term contracts. The prepaid method also allows total cost control and can be used by people below the age of 18. From the operators' point of view there is no billing risk with the prepaid method and costs can be saved due to the fact that credit checks are not required. Disadvantages from the users' point of view are the slightly to significantly higher usage-based costs of calls and the threat of the card credit lapsing, if calls are not made over a certain period.
It is also a significant disadvantage that replies can no longer be sent to incoming messages with mobile telephones with a prepaid card agreement when the credit is used up. Such replies cannot be sent, because when a credit check is carried out for the user in the switching center, lack of credit means that use of both the call service and the SMS service is refused. The situation is particularly problematic when the subscriber is required to sent a reply to a received message. The communication partner in question does not generally know that the reply could not be sent due to the expiration of the prepaid credit; and therefore, there is no reply.
Acceptance of usage costs (traffic charges) by the destination connection dialed is known as the R call or reverse charging in telecommunication technology; however, this principle is not appropriate for transfer to the SMS service. A current example of this is automatic reverse charging in X. 25 packet networks, with which the dialed packet connection accepts the volume costs of the data connection. In the public telephone network reverse charging is used for the operator-supported R call, with which the subscriber called agrees to accept the connection costs of the call in question. This feature of telecommunication networks is, of course, only possible with switching communication networks. Transfer to the short message service (i.e., acceptance of cost for SMS messages) is, therefore, not yet possible.
In view of the problem described, an object of the present invention is to specify a method for extending the possibilities for using mobile telephone services, in particular on a prepaid basis, and a system for implementing the method.